The dispensers in which the present invention will find application are generally known. They consist of a reciprocating piston that is manipulated by the user to force a liquid, or in some cases foam, product through a dispensing nozzle and out an outlet thereof. When the product is dispensed in this manner, a string of the product remains in the path through which the product was forced, and, particularly in certain dispenser configurations, this string of product can undesirably drip out of the dispensing nozzle. For example, most wall-mounted soap (or foamed soap) dispensers dispense the soap product through a downwardly extending dispensing nozzle, and the string of soap left in the dispensing nozzle might drip onto the floor or counter over which the dispenser is mounted. This not only wastes product, but is also undesirably messy.
Although dispensers are currently provided with so-called “suck back” or “back suction” features that function to draw the string of product out of the dispensing nozzle and into the more internal elements of the pump, there exists a need for a more efficient design of a dispenser for dispensing a soap product and drawing non-dispensed product back into the pump where it cannot cause dripping and other problems. In many of the existing dispensers that have a back suction feature, the suction element (i.e., the element(s) effecting the back suction feature) is in series with the pump piston, and a relatively large stroke length is necessary to actuate both the suction element and the piston. Also, in some dispensers employing a mesh screen to produce a foamed product, the residual foam product string in the dispensing nozzle is sucked back through the mesh screen to a location where foam is created in the next dispensing operation. Such configurations require the use of strong biasing members (e.g., spring bias on the piston) to pull the string or portion thereof through the mesh, and foam sucked back to the location of foam creation can compromise the integrity of the foam created in a subsequent dispensing. More efficient designs are needed to avoid the long stroke length and poor foam quality problems of the prior art, and this invention is directed toward alleviating these problems, and, more generally, toward providing a useful dispenser that will provide many benefits over prior art dispensers.